New 2-stroke engine won't start

DieselTech

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Yeah I opened it up and took the jug off too.

You're right that there's no way the piston was hitting the spark plug, so must have been a foreign object.

There were tiny particles of metal on the piston, but nothing obvious that could have those indentations I showed.

Weird thing is it looked like there hadn't been any combustion at all in there. Spark plug was clean, and no carbon residue anywhere
You should of took some pics for us!
 

Dood Surfston

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Looks like the pressure is 140 psi.

Is that in the expected range?
 

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Dood Surfston

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I wonder if the culprit might be bad gas then. There was a fuel shortage when I last filled my jerry can, so they might have been selling any old stuff.

I'll put it all back together and try with some fresh low-ethanol gas.
 

Greg58

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Definitely not a compression problem, maybe new fuel mix will get it started.
 

Chainlube

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I wonder if the culprit might be bad gas then. There was a fuel shortage when I last filled my jerry can, so they might have been selling any old stuff.

I'll put it all back together and try with some fresh low-ethanol gas.
If you have a clear jug, pour you gas into that and see if there is water on the bottom. It will look like a bubble.
 

Seantom22

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I'm having trouble starting my brand new 80cc 2 stroke bicycle engine. When I pedal up to speed and release the clutch I can hear the engine firing, and it fires as long as I keep pedalling, but dies as soon as I pull the clutch back in. I've tried again and again but the engine dies each time.

I'm following all the correct starting procedures as far as I can tell (20:1 gas/oil mixture, pump a bit of gas into carburetor, choke closed). The spark plug is definitely working, and I've double checked the wiring.

The problem might be low compression. I don't have a compression gauge, but I did the thumb-over-spark-plug hole compression test, and didn't feel much pressure. Even with the spark plug screwed in tight, I can push the bike forward and turn the motor over with a bit of effort.

Any suggestions on how to solve the issue?
Bad CDI by. Been there Too many times even with new kits. Check your spark.
 

Cjcapen

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Yes you could sand the head down flush, but you are going to ruin your squish band & that will cause a bunch of problems, like head looses its efficiency of removing heat from the piston & cylinder. If you did sand it down flush, you would have to recut your squish band in the cylinder head.
I'm having Trouble keeping my motor run when I take the gas line off the carb it fires and runs when I put it back on it dies
 
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